Method for depositing magnetically susceptible workpieces at preselected locations



May 28, 1968 H. ROSS ET AL 3,385,596

METHOD FOR DEPOSITING MAGNETICALLY SUSCEPTIBLE WORKPIECES AT PRESELECTEDLOCATIONS Filed Oct. 22, 19

5 Sheets-Sheet 1 INVENTORS HUGH ROSS FRANKLIN E. PARKE ATTORNEY y 8,1968 H. ROSS ETAL 3,385,596

METHOD FOR DEPOSITING MAGNETICALLY SUSCEPTIBLE WORKPIECES AT PRESELECTEDLOCATIONS Filed Oct. 22, 1965 3 Sheets-Sheet 2 INVENTORS HUGH ROSS FRALIN E.PARKE ATTORNEY May 28, 1968 H. ROSS ETAL METHOD FOR DEPOSITINGMAGNETICALLY SUSCEPTIBLE WORKPIECES AT PRESELECTED LOCATIONS 3Sheets-Sheet' 3 Filed Oct. 22, 1965 HUGH ROSS BY FRANKLIN INVENTORS EPARKE ATTORNEY United States Patent 3,385,596 METHOD FOR DEPOSITINGMAGNETICALLY SUSCEPTIBLE WORKPIECES AT PRESELECTED LOCATIONS Hugh Rossand Franklin E. Parke, Pittsburgh, Pa., as-

signors to Repair Manufacturing Co., Pittsburgh, Pa., a corporation ofPennsylvania Filed Oct. 22, 1965, Ser. No. 500,954 Claims. (Cl. 271-46)ABSTRACT OF THE DISCLOSURE This patent discloses methods for stackingworkpieces, such as sheets or pipe, of magnetically susceptiblematerial, such as steel. The workpieces are accurately stopped, withoutthe use of a physical abutment, by being brought into contact with aplurality of magnet-containing rollers, preferably undriven, so as to bedecelerated to a stop while in rolling contact with the rollers byabsorption of kinetic energy of the workpiece in cutting magnetic linesof flux, whereafter a force is exerted on the workpiece to disengage itfrom the rollers. The patent further describes force-applying means thatact, e.g., on a sheet in such manner that air is trapped under itsmiddle to cushion its descent to the pile or stack being formed.

This invention relates to a method for depositing workpieces at apreselected location at the exit end of a conveyor, and moreparticularly to a method for depositing magnetically susceptibleworkpieces, such as steel sheets, at said location wherein theworkpieces are conveyed successively at a relatively high rate of speedand decelerated substantially to a stop prior to their deposition atsaid location.

A large number of sheet handling devices are known which are adapted toreceive sheet material from a conveyor and either stack the sheets oneabove the other or place them on a second conveyor for transfer, forexample, in a different direction to equipment which subjects the sheetto further processing operations. In the case of magneticallysusceptible sheets, sch as steel, these handling devices haveconveniently employed magnetic rollers to facilitate suspending thesheets over the desired location prior to depositing them at saidlocation. Examples of these types of sheet handling devices will befound in U.S. Patents Nos. 2,005,200 and 2,015,809. An additionalexample of a sheet handling device of this type will be found in ourcopending US. patent application Ser. No. 365,615, filed May 7, 1964,now US. Patent No. 3,224,757, entitled Magnetic Sheet TransferringApparatus and assigned to the assignee of the present invention.

In operation, it is necessary for the above cited devices and most othersimilar devices to decelerate the sheet substantially to a stop prior todepositing it at said location. As is known, various methods haveheretofore been employed for decelerating and stopping the sheets. Forexample, in the case where the sheets are conveyed at a relatively slowspeed, it is conventional to provide an abutment positioned to beengaged by the forward edge of the sheet for stopping the sheet. Theabutment is positioned so that the sheet will fall after being stopped,to the desired location at substantially the same position as thepreviously stopped sheets. However, even at relatively slow speeds, theforward ends of the sheets were deformed when the sheet struck theabutment. The forward end portion of the sheet normally could not beused and was cut off.

To overcome the edge deformation problem, the abutment was yieldablysupported so as to absorb some of the kinetic energy of the sheetthereby reducing, although not completely eliminating, the sheet edgedeformation. In another sheet handling device wherein the sheets werereceived at a still higher velocity, conventional automobile or trucktires were employed, not too successfully, to protect the sheets againstthe forward edge deformation.

In a further attempt to eliminate the edge deformation problem, theabutment was removed and each sheet was released at a preselected timeinterval relative to the aforesaid desired location. Upon release, thesheet floated or fell to the stack. The most obvious problem associatedwith this method is timing the release of the sheet. The most obviousdisadvantage of this method is that the exposed face of the uppermostsheet in the stack will be defaced when the falling sheet strikes andslides over the exposed face.

Presently, there exists sheet handling apparatus which, as stated, iscapable of receiving steel sheets traveling at 250 feet per minutemaximum, and stack them without substantial marring. Although the sheettransfer speed of 250 feet per minute appears to be relatively high,present plans call for sheet transfer speeds up to 1500 feet per minuteand higher. It should be readily apparent, therefore, that dischargingsheets from a conveyor for stacking or for further transfer, withoutmarring or deforming the sheets is a real problem.

Accordingly, as an overall object, the present invention seeks toprovide a novel method for depositing workpieces at a preselectedlocation.

Another object of the invention is to provide a novel method fordepositing workpieces at a preselected location without marring ordeforming the sheets.

Still another object of the invention is to provide a method wherebysheets are accurately deposited relative to the previously depositedsheets, at a preselected location.

A further object of the invention is to provide a novel method wherebysheets traveling at relatively high rates of speed are deposited at apreselected location, accurately and without marring or deforming thesheets.

In the practice of the method of the invention, magnetically susceptiblesheets are conveyed successively by conventional means, such as aconveyor, to a preselected location adjacent the exit end of theconveyor. As each successive sheet passes into the region of saidpreselected location, it also passes through magnetic fields radiatingfrom magnetic rollers positioned adjacent thereto. Each successive sheetis therefore attracted into tangential contact with the rollers and isdecelerated substantially to a stop by absorption of its kinetic energyin cutting the magnetic lines of flux of the magnetic fields. After eachsheet has been decelerated, a force is applied thereto to disengage thesheet from the rollers and cause successive ones of the sheets to beplaced at said location.

In the preferred form of the invention, the rollers are initially spacedfrom each successive sheet and are moved into engagement with the sheetbeing decelerated to move the same toward the preselected location whilethe sheet is decelerated substantially to a stop.

In another embodiment of the invention, certain of the rollers employedto decelerate the sheet are moved toward the preselected location priorto moving the remaining ones of the rollers. In this manner, the sheetis arched prior to being disengaged from the rollers whereby the archedsheet takes advantage of trapped air to cushion its engagement with thesheet subsequently deposited at the preselected location.

In still another embodiment of the invention, the rollers are initiallyspaced from each successive sheet and are driven at a speed such thatits speed is substantially equal to the linear velocity of themagnetically susceptible sheets. The rollers are then moved intoengagement with the sheet being decelerated to move the same toward thepreselected location while the sheet is decelerated substantially to astop. By virtue of the fact that the rim speed of the rollers issubstantially equal to the linear speed of the sheets, the initialengagement therebetween will not cause marking of the sheets.

The present invention is particularly adapted for stacking or placingsheets of magnetically susceptible material at a preselected location.However, it is to be understood that the method of the invention may beemployed to deposit other magnetically susceptible workpieces of whichsteel pipe is but one example.

The above and other objects and advantages of the present invention willbecome apparent from the following detailed description by reference tothe accompanying drawings, in which:

FIGURE 1 is a schematic side view of the roller having magnet meansarranged to produce a magnetic field extending completely around itscircumference;

FIG. 2 is a schematic side view, similar to FIG. 1, illustrating theinitial tangential contact of a magnetically susceptible sheet with theroller;

FIG. 3 is a schematic side view, similar to FIG. 1, illustrating theeffect of the magnetic field in stopping the magnetically susceptiblesheet;

FIG. 4 is a front view, partially in cross section, illustrating aroller of the type described in conjunction with FIG. 1;

FIG. 5 is a cross-sectional view, taken transversely across aconventional magnetic conveyor, provided with rollers of FIG. 3;

FIGS. 6A, 6B and 6C are fragmentary side views of the conveyor of FIG.5, illustrating certain successive steps in the method of the invention;

FIG. 7 is a fragmentary cross-sectional view, similar to FIG. 5,illustrating a means for driving the rollers;

FIG. 8 is a side elevation view of apparatus, similar to that of FIG. 5,illustrating one embodiment of a method for stacking magneticallysusceptible sheets;

FIG. 9 is a side elevation view of apparatus, similar to that of FIG. 5,illustrating an alternative embodiment of a method for stackingmagnetically susceptible sheets; and

FIG. 10 is a side elevation view of apparatus, similar to that shown inFIG. 5, illustrating a method for stacking magnetically susceptiblesheets alternately at two spaced, preselected locations.

Referring now to FIG. 1, there is schematically illustrated a rollercarrying magnet means 22 arranged to produce magnetic lines of flux orforce indicated by the dashed lines 24, radiating about a central axis26 of the roller 20. The magnetic means 22 preferably comprise apermanent magnet although electromagnets may be used with equal utility.The magnetic means 22 is preferably arranged such that the magneticlines of flux 24 radiate in a torus-like configuration about the axis26. That is to say, the magnetic lines of flux 24 extend in thedirection of the central axis 26. The magnetic means 22 could, instead,be arranged to produce magnetic lines of flux which radiate in a seriesof cycloids such as illustrated by the dash-dot lines 28. The magneticlines of flux 28 would extend transversely of the central axis 26.

As will become apparent, a plurality of the rollers 20 are used todecelerate a magnetically susceptible sheet substantially to a stopprior to placing the sheet at a preselected location. The rollers 20'are preferably supported in a manner such that they are substantiallyfreely rotatable about the central axis 26 during deceleration of thesheet.

In FIG. 1, there is shown a fragment of a magnetically susceptible sheet30 which is moving, in the direction indicated by the arrow, into thefield of influence of the magnetic lines of flux 24. It is to beunderstood at this time, that the sheet 30 must be magneticallysusceptible, that is, capable of being attracted by a magnet, in orderthat the principles of the present invention may be practiced forstacking or placing the sheets 30 at a preselected location.Consequently, the sheet 30 may comprise, for example, ferromagneticsubstances such as iron, nickel and cobalt. The sheets 30 may also becomprised of substances which are normally non-magnetic but which arerendered magnetically susceptible by addition of sufficient amounts of aferromagnetic substance. Therefore, the phrase magnetically susceptiblesheets as used in the specification and the appcndant claims, isintended to include any and all substances which are capable of beingattracted by a magnet.

Returning now to FIG. 1, the sheet 30 is shown spaced from the roller20. As the sheet 30 enters the field of influence of the magnetic linesof flux 24, it will be subjected to a force which tends to pull theroller 20 and the sheet 30 toward each other. In accordance with thepresent invention and for reasons to be described later in thespecification, it is preferred to hold the sheet 30 in the planeillustrated and to move the roller 20 into engagement with the sheet 30.In FIG. 2, the sheet 30 is shown in tangential contact, as at 32, withthe roller 20. A number of the magnetic lines of flux 24 permeate thesheet 30 thereby attracting and maintaining the sheet 30 in tangentialcontact with the roller 20. Inasmuch as the sheet 30 is in contact withthe roller 20, the roller 20 will be caused to rotate in acounterclockwise direction by the movement of the sheet 30 to the leftof FIG. 2.

It has been discovered that the magnetically susceptible sheet 30 can bedecelerated from a relatively high rate of travel, as illustrated inFIG. 2, to a stop, as illustrated in FIG. 3, by passing the sheet 30 intangential rolling contact with a plurality of the magnetic rollers 20.The sheet 30 can be stopped within a relatively short distance and withgreat accuracy relative to a preselected location at which the sheet isto be deposited. For example, it us assume that the relative positionsof the roller 20 and the sheet 30 as shown in FIG. 2 represent theinstant at which the roller 20 contacts the sheet 30; and let us assumethat the relative positions of the roller 20 and the sheet 30 as shownin FIG. 3 represent that instant at which the sheet is decelerated to astop. Consequently, in FIG. 2 the leading edge 34 of the sheet 30 can beused as a reference point which during deceleration of the sheet 30 willmove through a distance, indicated in FIG. 3, by the dimension linelabeled L plus or minus 11. The distance L plus or minus n representsthe stopping distance or sheet travel during deceleration of the sheetto a stop. The letter L represents the average or mean stopping distancewhile the letter n represents the average variation in the stoppingdistance. Thus, for a given type of magnetically susceptible sheet, forexample, sheets of carbon steel, the stopping distance is generallyindicated by L-l-n. The variation in stopping distance occurs, forexample, because of variations in permeability from sheet-to-sheet;because of variations in friction normally associated with rotatablerollers; and because of a small amount of slippage which occasionallyoccurs between the sheet 30 and the roller 20.

Although the mannerin which the magnetic rollers function to absorb thekinetic energy of the sheet, is not completely understood, one possibleexplanation is as follows. As the sheet 30 moves relative to the axis26, see FIG. 2, the rollers 20 will rotate in a clockwise directionwhereby successive ones of the magnetic lines of flux 24 will be cut bythe sheet 30. Consequently, circulating currents (eddy currents) will bein induced in the sheet 30. As is known, energy is required to induceeddy currents in a conducting material. Furthermore, there areresistance losses accompanying these eddy current which dissipate aportion of the energy in the form of heat. In the case of the movingsheet 30, its kinetic energy supplies the energy necessary to induce theeddy currents created as the sheet 30 cuts the magnetic lines of flux.The kinetic energy of the sheet 30 is, therefore, absorbed anddissipated in the form of heat. By increasing the number of magneticrollers, the amount of kinetic energy absorbed can, of course, beincreased. Consequently, it can be said that the sheet 30 is deceleratedto a stop by absorption of its kinetic energy in cutting the aforesaidmagnetic lines of flux.

Reference is now directed to FIG. 4 whrein thre is illustrated a rollerassembly 40 constructed to produce magnetic lines of flux radiating in atorus-like configuration about its axis. The roller assembly 40comprises two magnetic rollers 42, both of which are identical inconstruction. Each of the magnetic rollers 42 comprises pole pieces 44,46 having a magnetic disc 48 interposed therebetween. A plurality of:bolts 50 retain the pole pieces 44, 46 and the magnetic disc 48 in thesandwiched configuration illustrated. The pole piece 44 has a threadedhub 52 on which is threaded a disc 54. Interposed between the outeredges of the disc 54 and the pole piece 44 is an O-ring 56. The O-ring56 is compressed between the pole piece 44 and the disc 54 whereby itsouter peripheral edge is extruded beyond the outer surface of the disc54 and the pole piece 44. The overall arrangement is such that themagnetically susceptible sheet 30 will contact only the outer peripheraledge of the O-ring 56 and thereby be maintained spaced from the polepieces 44, 46. This construction, of course, prevents marking the sheets30 by preventing contact between the hard metal pole pieces 44, 46 andthe surface of the sheet 30.

Extending through the pole pieces 44, 46 and the magnetic disc 48 is acylindrical bearing member 58 having a bore 60 extended axiallytherethrough. The cylindrical bearing member 58 preferably is formedfrom plastic material such as nylon or Teflon, but, could, instead, beformed from other suitable bearing forming materials.

Extending through the bores 60 of the cylindrical hearing members 58 isa shaft 62 having one end secured to an arm 64. The shaft 62 includes aradial flange 66 which is positioned between the arm 64 and the bearingmember 58 of the inner magnetic roller 48. The opposite end of the shaft62 is threaded and receives suitable fasteners, such as bolts 68, whichserve to retain the magnetic rollers 42 on the shaft 62.

The inner diameter of the bores 60 is preferably greater than the outerdiameter of shaft 62, thereby permitting each of the magnetic rollers 42to be angularly displaced relative to the central axis 26 so as toconform to any distortions in the sheet 30. Inasmuch as the innerdiameter of the bore 60 is greater than the outer diameter of the shaft62, the rollers 42 are substantially freely rotatable about the centralaxis 26.

As stated above and as an alternative arrangement, it is possible toarrange magnets within a roller whereby the magnetic lines of fluxradiate in a series of cycloids around the periphery of the roller, asillustrated by the flux lines 28 of FIG. 1.

As an example of how the roller assembly 40 is employed to practice themethod of the invention, reference is now directed to FIGS. 5 and 6Awherein two of the roller assemblies 40 are shown mounted on aconcentional magnetic conveyor 76. The magnetic conveyor 76 comprises aframe formed from side channels 78 and upper and lower falls 80, 82. Aroller 84, in this instance being an idler roller, is shown rotatablyconnected to the side channels 78 by means of journals 86. It is to beunderstood that a second roller, which in this instance is a driveroller, would be rotatably supported at the opposite end of the magneticconveyor 76 and driven by a suitable drive motor. Extending along theupper and lower walls 80, 82 and around the rollers supported at the endof the magnetic conveyor 76 is an endless drive belt 88 which ispreferably formed from a leather-like material rendered magnetic by theaddition of ferromagnetic substances such as iron particles.

Carried within the magnetic conveyor, that is secured to the inner faceof the lower wall 82, is a series of magnets which are preferably of thepermanent type but which could, instead, be electromagnets. The magnets90 are so positioned across and along the length of the bottom wall 82such that a plurality of magnetic fields are provided which attract thelower reach of the drive belt 88 into engagement with the lower wall 82.Additionally, the magnetic fields of the magnets 90 also serve toattract the magnetically susceptible sheet 30 into engagement with thedrive belt 88 thereby conveying the sheet 30 along the conveyor 76 asillustrated in FIG. 6A.

As can be seen in FIG. 5, one of the roller assemblies 40 is supportedon each side of the conveyor '76. Specifically, the arms 64 are securedto a common shaft 92 which is rotatably supported in pillow blocks Msecured to the magnetic conveyor 76. A connecting arm 96 is rigidlysecured to the common shaft 92, preferably at a central locationthereon. Operatively connected to the connecting arm 96 is actuatingmeans 98 which serves to rotate the common shaft 92 about its centralaxis thereby causing the roller assemblies 40 to be moved toward andaway from the sheet 36 along an arcuate path of travel, as will bedescribed. The actuating means 98 may comprise, for example, a pneumaticcylinder 100 of the type requiring forces to extend and retract thepiston shaft 102 thereof. Associated with the pneumatic cylinder 100 isa solenoid operated control valve 104 which operates to extend andretract the shaft 102 when and as desired.

As stated above, the method of the present invention includes a stepwherein a force is exerted on the sheet to disengage the sheet from therollers. This force is conveniently provided by a stripping roller 106carried at the end of the arm 64. The stripping roller 106 is preferablyformed from materials which will not mar the sheet 30. Such materialsare, for example, rubber and plastics.

The preferred embodiment of the present invention is illustrated inFIGS. 6A, 6B and 6C. In FIG. 6A, the sheet 30 is passed adjacent-beneathin this instancethe roller assembly 40. Notice that the roller 20 isvertically spaced from the sheet 30. At a preselected time, theactuating means 98 is activated to lower the roller assembly 40 intoengagement with the sheet 36, as shown in FIG. 6B, whereby the sheet 30is decelerated substantially to a stop by absorption of its kineticenergy in cutting the magnetic lines of flux, as explained above. Atthis time, the sheet 30 is disengaged from the magnetic conveyor 76 sothat the sheet 30 is suspended entirely by means of the magnetic rollers20. After the sheet 30 has been decelerated substantially to a stop, thedownward movement of the stripping roller 106 disengages the sheet 39from the roller assembly 40 so that the sheet 30 will drop to thepreselected position.

It should be understood at this time that the roller assemblies 40 arelowered in one continuous motion from the position shown in FIG. 6A to aposition corresponding substantially to that shown in FIG. 6C.Thereafter, the activating means retracts its piston shaft 102 to returnthe roller assembly 40 to the starting position of FIG. 6A preparatoryto depositing the next successive sheet 30.

In the case where the surface of the sheet 30 is relatively easilymarked, it is desirable, as shown in FIG. 7, to provide a drive roller108 rotatably supported on the conveyor 76, as by means of a journalblock 110. The drive means, schematically illustrated at 112, is used torotate the magnetic rollers 20 at a speed such that its rim speed issubstantially equal to the linear speed of the sheet 30. Thus, when themagnetic roller-s 20 are lowered, their engagement with the sheet 30 isaccomplished without marring the sheet 30. It is to be noted that whenthe magnetic rollers 20 are disengaged from the drive roller 108, theyare substantially freely rotatable during deceleration of the sheet 30.The drive means 112 make take any one of a variety of forms. It may, forexample, comprise a set of gears suitably connected to the drive roller108 and arranged to be driven by the main drive of the conveyor 76.Alternatively, the shaft 62 of the roller assembly 40 may be rotatablymounted on the arm and a suitable drive arrangement provided forrotating the shaft 62. Inasmuch as the rollers are freely rotatable onthe shaft 62, as explained above in conjunction with FIG. 4, forcedrotation of the shaft 62 will cause the rollers 29 to be rotated onlywhen the rollers 20 are not engaged with the sheet 30. When the rollers20 are engaged with the sheet 30, however, the magnetic attractionbetween the rollers 20 and the sheet 30 prevents the roller 2% frombeing rotated by the shaft 62.

Referring now to FIG. 8, a decelerating unit 113 is shown comprising themagnetic conveyor 76 having a plurality of the roller assemblies locatedat uniformly spaced points along its length. An actuating means 98 isoperatively connected to each roller assembly 40, as described above.The solenoid operated control valves 104 are supplied with operatingfiuid by means of a common conduit 114. A control circuit, indicatedschematically at 116, includes a conduit 118 carrying a multi- Htionally, the sensing unit 120 may be adjustably connected to theconveyor 76 whereby the sensing unit 120 is positioned at any desiredlocation along the length of the conveyor, or a plurality of the units120 may be used. Conductor 122 electrically connects the sensing unit120 to the control circuit 116. The control circuit 116 is such that theroller assemblies may be lowered and raised individually or inpreselected groups according to the length of the sheet beingdecelerated.

The decelerating unit 113 is positioned adjacent the exit end of aconventional sheet conveyor 126. The decelerating unit 113 is alignedwith the sheet conveyor 126 so as to receive, in succession, the sheetsconveyed by the conveyor 126.

In FIG. 8, a magnetically susceptible sheet 30A has been decelerated toa stop by a preselected set of the rollers, indicated by the bracket128. Adjustment of the control circuit 116 serves to activate theappropriate ones of the actuating means 98 to lower the preselected setof rollers 128. The set of rollers 12.8 are being lowered and areillustrated in a position wherein the stripping rollers are about todisengage the sheet 30A from the roller assemblies.

It is to be noted at this time that the position of sheet 30A relativeto the set of rollers 128 is such that a trailing end portion 130- ofthe sheet 30A is unsupported, that is, none of the roller assemblies 40support the same. Furthermore, the sheet 30A has been displaced out ofthe plane of the subsequent sheets 30B and 30C. Consequently, duringdeceleration, the sheet 30A is lowered so that a leading end portion 132of the next successive sheet 30B overlaps the trailing end portion 130of the decelerated sheet 30A. Hence, the sheet 30B is permitteduninterrupted travel along the conveyor 76 during the time required tolower the set of rollers 128 so as to place the sheet 30A on a stack ofsheets 134 and to raise the set of rollers 128 to their normal elevatedposition. As the leading edge of the sheet 30B reaches the first rollerassembly 40 of the set of rollers 128, the set of rollers 128 are up outof the path of travel of the sheet 30B.

As a consequence of this method of placing the sheets 30 on the stack134, the sheets 30 may be conveyed on the conveyor 126, for example,with the trailing edge of the sheet 351B adjacent to the leading edge ofthe sheet 30C.

An alternative embodiment of the present method is illustrated in FIG.9. In this embodiment, certain of the roller assemblies 40 of the set ofrollers 128 are lowered in advance of the lowering of the remainingroller assemblies 40 whereby the sheet being decelerated is arched. Inthe arched configuration, the sheet may take advantage of trapped airacting as a cushion to ease the sheet onto the stack.

In FIG. 9, for example, the control circuit 116 activates, in sequence,the actuating means 98 of the opposite end roller assembly 40A, of theroller assembly 40B and finally of the roller assembly 40C. As a result,the sheet 30A is given a downward concave, arched configuration wherebyas the sheet 30A falls to the stack 134, air trapped beneath the sheet,will cushion its impact with the uppermost sheet in the stack 134.Furthermore, the trailing end portion will again be displaced out of theplane of the next successive sheet 30B which, is permitted uninterruptedtravel along the conveyor 76. It should be noted, however, that in thiscase, the trailing end portion 130 is lowered at a considerably fasterrate than the trailing end portion 130 in FIG. 8. Consequently, thespacing between the trailing and leading edges of successive sheets maybe considerably less than the spacing of the sheets 30 in the method ofFIG. 8. In the extreme, the sheets 30B and 30C of FIG. 9 could bedisposed in end-to-end abutted relation if desired.

In FIG. 10 there is illustrated a decelerating unit 134 which is similarto the units 113 of FIGS. 8 and 9, with the exception that the unit 134is approximately twice as long as the units 113. Therefore, thedecelerating unit 134 is capable of placing sheets alternately at eitherof the aligned receiving tables 136, 138. That is to say, a firstpreselected set of rollers 149 is employed to place successive sheets onthe receiving table 136. Thereafter, a second preselected set of rollers142 is employed to place the sheets on the receiving table 138 while thestacked sheets on the receiving table 136 are removed. The sets ofrollers 140, 142 will be used alternately thereby providing continuousoperation of the equipment delivering the sheets to the conveyor 126.

The following example is included to illustrate the seeed with whichmagnetically susceptible sheets may be substantially stopped and placedat a preselected location and the accuracy achieved in placing the sheetat said preselected location. A carbon steel sheet was used which was 8feet long, 4 feet wide, A; inch thick and which weighed pounds. Thissheet was conveyed at a linear velocity of 450 feet per minute to adecelerating unit very similar to the unit illustrated in FIG. 8. Thesheet was passed beneath the magnetic rollers and at a preselected time,the magnetic rollers were lowered into engagement with the sheet. Thissheet was repeatedly stopped within eighteen inches of sheet travel withan accuracy of plus or minus one inch.

It is to be noted at this time, that the methods of the invention areapplicable to placing sheets on other conveyors which serve to conveythe sheets, for example, in a different direction to other areas of theplant for further processing operations. Further-more, the methods ofthe invention are also applicable to the condition wherein the sheetsare conveyed standing on one edge as opposed to being laid fiat asillustrated in the drawings. Still further, the methods of the inventionare also applicable to depositing other magneticaly susceptibleworkpieces, such as, pipes and conduits of various cross-sectionalconfigurations. The appendant claims are intended to include all suchoperations.

Although the invention has been shown in connection with certainspecific embodiments, it will be readily apparent to those skilled inthe art that various changes may be made to suit requirements withoutdeparting from the spirit and scope of the invention.

We claim as our invention:

1. A method for placing magnetically susceptible workpieces successivelyat a preselected location adjacent the exit end of a conveyor adapted toconvey said workpieces in succession, comprising the steps of passingsuccessive ones of said workpieces adjacent rollers which are disposedat said preselected location and which carry magnet means arranged toproduce magnetic lines of flux radiating about the axes of the rollers,whereby each successive moving workpiece will be attracted intotangential contact with a number of the rollers and will be deceleratedsubstantially to a stop while in rolling contact with the rollers byabsorption of its kinetic energy in cutting said magnetic lines of flux,and after each workpiece has been decelerated, exerting a force thereonto disengage the workpiece from said rollers and cause successive onesof said workpieces to be placed at said preselected location.

2. The method of claim 1 wherein said rollers are freely rotatable abouttheir axes during deceleration substantially to a stop of eachsuccessive moving sheet.

3. The method of claim 1 wherein said magnetic lines of fiux radiate ina torus configuration about the axes of said rollers.

4. The method according to claim 1 wherein the axes of said rollersextend transversely of the direction of travel of said workpieces andwherein said axes of said rollers are substantially parallel to eachother.

5. The method according to claim 1 wherein said workpieces comprisemagnetically susceptible sheets and wherein the rollers of said numberof rollers are moved such that each successive moving sheet is movedtoward said preselected location while each successive moving sheet isdecelerated substantially to a stop.

6. The method according to claim 1 wherein said workpieces comprisemagnetically susceptible sheets and wherein certain of the rollers ofsaid number of rollers are moved toward said preselected location priorto moving the remaining ones of the rollers of said number of rollerswhereby each successive moving sheet is arched prior to being disengagedfrom said number of rollers.

7. The method according to claim 6 wherein each suecessive sheet isgiven a downward concave arch whereby its trailing end portion is moveddownwardly out of the way of the leading edge of the next successivemoving sheet.

8. The method according to claim 1 wherein initially, said rollers arespaced from each successive moving workpiece and wherein the rollers ofsaid number of rollers are moved into engagement with each successiveworkpiece to move the same toward said preselected location while eachsuccessive moving workpiece is being decelerated substantially to astop.

9. In the method for discharging magnetically susceptible workpieces ata preselected location wherein said magnetically susceptible workpiecesare conveyed in succcssion at a high rate of travel to said preselectedlocation, the step of stopping each successive moving workpiece prior todeposition at said preselected location by passing each successivemoving work-piece adjacent freely rotatable rollers carrying magnetmeans arranged to produce magnetic lines of flux which radiate about therotational axes of the rollers, whereby each successive moving workpiecewill be attracted into tangential rolling contact with a number of therollers and will be decelerated substantially to a stop while in rollingcontact with said number of the rollers by absorption of its kineticenergy in cutting said magnetic lines of flux.

10. A method for placing magnetically susceptible shets successively inface-to-face contact at a preselected location adjacent the exit end ofconveyor means adapted to convey said sheets such that the trailing edgeof each sheet is closely adjacent the leading edge of the adjacentsheet, comprising the steps of passing successive ones of said sheetsadjacent rollers which are disposed at said preselected location andwhich carry magnet means arranged to produce magnetic lines of fluxradiating about the axes of the rollers, whereby each successive movingsheet will be attracted into tangential contact with a number of saidrollers and will be decelerated substantially to a stop by absorption ofits kinetic energy in cutting said magnetic lines of flux, the positionof each successive moving sheet relative to said number of said rollersbeing such that a trailing end portion thereof is unsupported,displacing certain rollers of said number of said sheets toward saidpreselected location during deceleration of the sheet to move at leastsaid trailing end portion out of the plane of the next successive sheet,whereby the leading edge of the next successive sheet will overlap thetrailing end portion of the sheet being decelerated, and after eachsuccessive sheet has been decelerated, exerating a force thereon todischarge the sheet from said number of said rollers and causesuccessive ones of said sheets to be placed at said preselectedlocation.

References Cited UNITED STATES PATENTS 2,183,798 12/ 1939 Theiss 271-742,312,357 3/1943 Odquist et al 271-74 3,132,858 5/1964 Bernard 271-683,224,757 12/ 1965 Parke et al 271-74 2,957,691 10/1960 Williams 21463,051,479 8/1962 Gore 214-6 ALLEN N. KNOWLES, Primary Examiner.

